I just can't seem to make grid fill work for me
CtrlF &gt; Grid Fill works like this:


It calls the (white) active vertex when it is invoked a &quot;corner&quot;. (Red zones)
It takes the next Span - 1 vertices, and bridges them to their opposite numbers. (Lilac)
It skips another corner, and then connects what's left cross-ways. (Green).

This results in Span face-loops across the piece, (up, in the picture :) ) and 4 corners.
The illustration shows Spans of 4,3,2 and 1 on a 16-circle, with the active vertex in white.
(The Offset setting steps the starting-point around the perimeter.)
So you can see, to get a tidy result from Grid Fill, you need:

An even number of vertices
A reasonably nice correspondence of vertices to their opposite numbers, once you've decided where the first corner should go.

In your case, you need to fix the second condition.